Agricultural round balers have been used for several decades to collect and bind crop material so as to facilitate the storage of crop material for later use. Generally, a mower or mower-conditioner cuts the crop and arranges it in a windrow for drying. Later, an agricultural tractor pulls a baler over the windrow to collect the crop material. The baler's windrow pickup gathers the cut and windrowed crop and lifts it into the baling chamber. The baling chamber consists of a pair of opposing sidewalls with a series of belts that rotate and compress the crop material into a cylindrically shaped bale. When the bale has achieved a desired size and density, the operator wraps the bale to ensure that the cylindrical and compact nature of the bale is maintained. There are many wrapping materials and methods of wrapping the bale depending on a variety of factors. Initially, twine was used to wrap the bale. Later net-wrap and silage sheets were introduced. After the bale is bound or wrapped, it is ejected from the baler for later pickup by the farmer.
As previously mentioned, there are a variety of agricultural round balers. A general example of this device is illustrated by the New Holland Roll-Belt™ Round Baler model number 678 manufactured by New Holland North America, Inc. Generally, round balers are pulled by an agricultural tractor and receive rotational power from the tractor's power-take-off shaft positioned at the rear of the tractor. The energy is transmitted to a gearbox positioned on the baler. Some balers also use a hydraulic motor and pump arrangement to provide energy to the various baler elements such as the various rollers and belts. As previously discussed, a variety of methods are used to wrap the bale. Relatively recently, the use of netting or net-wrap has been introduced. It is desirable for bales to maintain a cylindrical shape, however this has been especially difficult near the edge of the cylindrical bale. It is difficult for twine to remain on the edge of the bale as well as mechanically placing the twine in that position. Recently attempts have been made to extend a portion of the net-wrap around the edge of the round bale. By allowing a slight portion of the net-wrap to extend over the edge of the bale, the appearance of the round bale is improved. Furthermore, the bale is afforded additional protection.
The tension that is applied to the net is determining for a fast and optimal spreading of the net-wrap over the edges of the bale. A tension that is too small will typically result in the net not spreading out, but remaining bundled in the centre of the bale. As a result, when it takes a long time to achieve the optimal tension, a significant amount of net is wrapped in a bundle around the centre of the bale thereby inefficiently using the net material. When the tension is too high, the net will apply to much tension on the supply system and will prevent movement of the supply system towards the baling chamber. That way, no supply of net will be possible and the feeding of net towards the formed bale will not occur.